The present invention relates to an optical recording medium including a substrate and a signal recording layer provided on the substrate and in which an information signal recorded on the signal recording layer is reproduced optically or by detecting a change of the reflected light focused onto the signal recording layer, and to a disc cartridge encasing the optical recording medium.
As one of the conventional recording media for audio and video information, optical discs, from which recorded information is read using a light beam or to which information is written using a light beam, are widely used. Since such an optical disc is formed from a single plate-like substrate, it can easily be handled and has a larger storage capacity than other recording media such as magnetic tapes, etc. Therefore, the optical discs are widely used as media for recording audio and video information, computer-processed data, etc.
Information processing units, such as computers, have been designed more and more compact with an increasingly smaller internal space of installation for a recording and/or reproducing apparatus using an optical recording medium such as an optical disc or the like. That is, there is a demand for a smaller design of such a recording and/reproducing apparatus.
There are various types of portable or carry-on recording and/or reproducing apparatuses for recording and/or reproduction of audio and video information. For a higher portability, it is also demanded that the apparatuses be of a more compact design.
For such a smaller recording and/or reproducing apparatus, a recording medium used in the apparatus should be correspondingly smaller while having a larger storage capacity.